Futibatinib — Drug Monograph

Brand names: Lytgobi

Drug class: Tyrosine Kinase Inhibitor

Mechanism of Action

Covalent, irreversible pan-FGFR1-4 inhibitor. Unlike reversible FGFR inhibitors (pemigatinib, infigratinib), futibatinib forms a covalent bond with Cys492 in the FGFR2 kinase domain P-loop, maintaining activity against secondary kinase-domain resistance mutations (e.g., FGFR2 V565F gatekeeper mutation, FGFR2 L617V) that emerge after treatment with reversible FGFR inhibitors.

FDA Indications

• FGFR2 fusion or rearrangement-positive unresectable locally advanced or metastatic intrahepatic cholangiocarcinoma after ≥1 prior line of systemic therapy (FDA approved September 2022; FOENIX-CCA2: 42% ORR, median DOR 9.5 months)

Common Side Effects

• Hyperphosphatemia (85% — virtually universal; manage with phosphate binders)
• Diarrhea (38%)
• Nausea (37%)
• Dry eye (27%)
• Fatigue (26%)
• Onycholysis/nail toxicity (22%)
• Alopecia (21%)
• Palmar-plantar erythrodysesthesia
• Elevated AST/ALT

Clinical Pearl

Futibatinib's covalent mechanism provides an advantage over reversible FGFR inhibitors in patients who have acquired secondary resistance mutations (e.g., FGFR2 V565F). Hyperphosphatemia is essentially universal due to FGFR1-mediated FGF23 signaling disruption — proactive management with dietary restriction and phosphate binders is required from day one.

Related Therapies & Mechanisms

• Regorafenib (Stivarga) — Tyrosine Kinase Inhibitor · Gastric
• Afatinib (Gilotrif) — Tyrosine Kinase Inhibitor
• Alectinib (Alecensa) — Tyrosine Kinase Inhibitor
• Alpelisib (Piqray) — Tyrosine Kinase Inhibitor